JP4455432B2 - Ion milling apparatus and ion milling method - Google Patents

Description

  The present invention relates to an ion milling apparatus and an ion milling method for producing a sample observed with a scanning microscope (SEM), a transmission microscope (TEM), or the like.

  An ion milling device is a device for polishing the surface or cross section of metal, glass, ceramic, etc. by irradiating an argon ion beam, etc., and a pretreatment device for observing the surface or cross section of a sample with an electron microscope It is suitable as.

  In cross-sectional observation of a sample using an electron microscope, conventionally, the vicinity of the part to be observed is cut using, for example, a diamond cutter, a thread saw, etc., and then the cut surface is mechanically polished and attached to a sample stage for an electron microscope. I was observing.

  In the case of mechanical polishing, for example, a soft sample such as a polymer material or aluminum has a problem that the observation surface is crushed or deep scratches remain due to abrasive particles. In addition, for example, a hard sample such as glass or ceramic is difficult to polish, and a composite material in which a soft material and a hard material are laminated has a problem that cross-sectional processing is extremely difficult.

  In contrast, ion milling enables polishing of hard samples and composite materials that can be processed without damaging the surface morphology even with soft samples. There is an effect that a mirror-shaped cross section can be easily obtained.

  Patent Document 1 describes a sample holder and a holder fixture of an ion milling apparatus.

  In Patent Document 2, an ion beam irradiation means for irradiating a sample with an ion beam disposed in a vacuum chamber and an inclination having an inclination axis disposed in the vacuum chamber and in a direction substantially perpendicular to the ion beam. A sample preparation apparatus comprising a stage, a sample holder disposed on the inclined stage and holding the sample, and a shielding material positioned on the inclined stage and blocking a part of an ion beam that irradiates the sample There is described a sample preparation apparatus in which a sample processing by the ion beam is performed while changing an inclination angle of the inclination stage, and an optical microscope for adjusting the position of the sample is attached to an upper end portion of the sample stage drawing mechanism. ing.

JP-A-9-293475 JP 2005-91094 A

  In a conventional ion milling apparatus, when a sample holder to which a milled sample is fixed is attached to an SEM sample stage support part, an SEM sample stage for attachment is provided between the sample holder and the SEM sample stage support part. The sample holder which fixed the sample milled to the stand was adhered and fixed, and there was a problem that the distance between the two became long and the work was troublesome.

  In view of this point, the present invention provides an SEM sample stage that has been used for attachment between the sample holder and the SEM sample stage support part when the sample holder to which the sample is fixed is attached to the SEM sample stage support part. The purpose is to reduce the distance between the two so that the sample holder can be placed close to the SEM sample stage support, and to easily observe the milled sample with the SEM. And

The present invention provides an ion beam source that irradiates a sample with an ion beam, a sample holder that fixes the sample, a sample holder fixture that fixes the sample holder, the sample holder, and the sample holder A mask that shields a part of the fixed sample, a sample rotation mechanism that rotates the sample holder, a sample mask unit that includes a mask position adjustment unit that adjusts a shielding positional relationship between the mask and the sample, and the mask In an ion milling device equipped with an optical microscope for observing the shielding positional relationship between the sample and the sample,
The sample holder has a cross-sectional shape with chamfered corners, and can be rotated by the sample rotation mechanism when attached to the sample rotation mechanism.
One surface side of the cross section of the sample holder is a sample fixing surface,
A said surface in contact with the sample fixing surface perpendicular of the sample holder, the rear surface of the polished to a surface to be observed of the sample, because the male screw portion provided in the SEM sample stage support is screw inserted directly Screw holes are provided ,
The female screw hole, the male screw portion by being threaded directly inserted, wherein the sample holder into which a sample was fixed is to be fixed directly to the SEM sample stage without using the SEM sample stage An ion milling device is provided.

According to the present invention, when the sample holder to which the sample is fixed is attached to the SEM sample stage support part, the SEM sample stage that has been used for attachment is not provided between the sample holder and the SEM sample stage support part. It can be attached, and therefore the distance between the two can be shortened so that the sample holder can be placed close to the SEM sample stage support, and the milled sample can be easily observed with the SEM. .

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a configuration of an ion milling apparatus according to the present invention, and shows a state in which a sample mask unit and a sample holder fixture are installed inside a vacuum chamber. Below, the case where an argon ion beam is irradiated from an ion source is demonstrated. Therefore, hereinafter, the ion beam means an argon ion beam, but the present embodiment is not limited to the argon ion beam.

  The current density of argon ions in the ion source 1 of argon ions is controlled by the ion source controller 7. The vacuum chamber 15 can be in a vacuum or atmospheric state by controlling the vacuum exhaust system 6 by the vacuum exhaust system controller 9 and can maintain the state.

The sample fine movement base 5 is configured to fix the sample holder 23 for fixing the sample 3 and to be able to rotate and tilt at an arbitrary angle with respect to the optical axis of the ion beam. It is controlled by the fine movement control unit 8. By rotating and tilting the sample fine movement base 5, the sample 3 fixed to the sample holder 23 can be set at a predetermined angle with respect to the optical axis of the ion beam. Further, the sample mask unit fine movement mechanism 4 is configured to be movable in the front-rear and left-right directions, that is, in the X direction and the Y direction with respect to the optical axis of the ion beam.

  The sample fine movement base 5 is disposed on a flange 10 that also serves as a part of the container wall of the vacuum chamber 15 via a rotation mechanism, and the flange 10 is pulled out along the linear guide 11 to open the vacuum chamber 15 to an atmospheric state. Sometimes, the sample fine movement base 5 is configured to be pulled out of the vacuum chamber. In this way, the sample stage drawing mechanism is configured.

  The configuration of the sample mask unit main body will be described with reference to FIG. 2A is a plan view, and FIG. 2B is a side view. In the embodiment, a configuration in which at least the sample holder 23 and its rotation mechanism, and the mask 2 and its fine adjustment mechanism are integrally formed is referred to as a sample mask unit (main body) 21. In FIG. 2, a sample holder rotating ring 22 and a sample holder rotating screw 28 are provided as a rotating mechanism of the sample holder 23 so that the sample holder can be rotated perpendicularly to the optical axis of the ion beam.

  The sample mask unit 21 has a mechanism that can finely adjust the position and rotation angle of the mask, and can be attached to and detached from the sample mask unit fine movement mechanism 4.

  The mask 2 is fixed to the mask holder 25 by a mask fixing screw 27. The mask holder 25 moves along the linear guide 24 by operating a mask fine adjustment mechanism (that is, a mask position adjustment unit) 26, thereby finely adjusting the positions of the sample 3 and the mask 2. The sample holder 23 is inserted and fixed to the sample holder rotating ring 22 from the lower side. The sample 3 is bonded and fixed to the sample holder 23. The position of the sample holder 23 in the height direction is adjusted by the sample holder position control mechanism 30, and the sample holder 23 is brought into close contact with the mask 2.

  The sample holder rotating ring 22 is configured to rotate by turning the sample holder rotating screw 28, and the reverse rotation is returned by the spring pressure of the spring 29.

  FIG. 3 shows another example of the sample mask unit 21. In this example, the sample holder fixing bracket 35 is used, and the other configuration is basically the same as the example shown in FIG. FIG. 3A shows a state in which the sample holder 23 to which the sample 3 is fixed is mounted in the sample mask unit 21, and FIG. 3B shows that the sample holder 23 to which the sample 3 is fixed is removed from the sample mask unit 21. Indicates the state.

  FIG. 4 is a diagram showing details of the sample holder 23 to which the sample 3 is fixed. FIG. 4A is a front view 51 of the sample holder 23 to which the sample 3 is fixed. FIG. 4B is a diagram showing a state in which the sample holder 23 is attached to the SEM sample stage support 34.

  As shown in these drawings, a screw hole 52 for fixing to the SEM sample stage support portion is provided on the back surface 51 of the sample holder 23 (the surface opposite to the mirror polished surface 39 of the sample 3). As shown in FIG. 4B, the SEM sample stage support part 34 is provided with a screw part 53 that is directly screwed into the screw hole 52, and the screw part 53 is screwed directly into the screw hole 52. .

  FIG. 6 shows a state in which the sample holder 23 is directly screwed (screwed) into the SEM sample stage support portion 34 through the screw portion 53 and the screw hole 52 and fixed. In this state, the polished surface of the sample 3 is observed by SEM.

  FIG. 5 is a diagram showing a structure of a conventional example for comparison with the present embodiment. In the conventional example, the screw part 54 provided on the SEM sample stage support part 34 is not directly screwed into the screw hole 52, but the SEM sample stage 33 which is an intermediate material is provided and provided on the SEM sample stage 33. A screw portion (not shown) to be inserted into the screw hole 52 is provided on the SEM sample stage 33 and the screw portion is inserted into the screw hole 52. Therefore, there is a disadvantage that the distance between the sample 3 and the SEM sample stage support 34 becomes long. In this embodiment, since the screw part 53 provided on the SEM sample stage support part 34 is directly screwed into the screw hole 52, there is an advantage that the distance between the sample 3 and the SEM sample stage support part 34 can be reduced. is there. Further, the troublesome work of bonding and fixing the sample holder that fixes the sample milled on the SEM sample stage is not required.

As described above, a back surface 51 of the sample holder 23, the surface facing the opposite side of the polished to a surface 39 to be observed in the sample 3, the screw portion 53 provided on SEM sample stage support 34 are directly A screw hole 52 into which a screw is inserted is provided . Then, by directly inserting the screw portion 53 into the screw hole 52 , the sample holder 23 to which the sample 3 is fixed is directly supported by the SEM sample table without using an intermediate material (for example, the SEM sample table 33 in the conventional example). It can be fixed to the part 34.

FIG. 7 is an explanatory view showing a method of making the cross section of the sample parallel to the mask.
The sample holder rotating screw 28 is rotated to adjust the position in the X1 direction, and fine adjustment is performed under the microscope as described later so that the cross section of the sample 3 and the ridge line of the mask 2 are parallel. At this time, the fine adjustment mechanism 26 is set so that the cross section of the sample 3 slightly protrudes from the mask, for example, approximately 50 μm.

  FIG. 8 shows the configuration of the sample stage drawing mechanism 30. The sample stage drawing mechanism 30 includes a linear guide 11 and a flange 10 fixed to the linear guide 11, and the sample fine movement base 5 fixed to the flange 10 is drawn from the vacuum chamber 15 along the linear guide 10. In accordance with this operation, the sample mask unit fine movement mechanism 4 provided with the sample mask unit 21 installed on the sample fine movement base 5, that is, the mask 2, the sample holder 23, and the sample 3 are pulled out from the vacuum chamber 15 integrally. .

In this embodiment, the sample mask unit fine movement mechanism 4 provided with the sample mask unit 21 has a configuration that is detachably fixed to the sample fine movement base 5. Therefore, when the sample mask unit fine movement mechanism 4 provided with the sample mask unit 21 is pulled out of the vacuum chamber 15, the sample mask unit fine movement mechanism 4 provided with the sample mask unit 21 is made detachable from the sample fine movement base 5. The (Removal standby of sample mask unit 21)
FIG. 8 shows a state in which the sample mask unit fine movement mechanism 4 provided with the sample mask unit 21 is detached from such a detachable state. This attachment / detachment is performed manually or with an appropriate instrument.

On the other hand, as shown in FIG. 9, the optical microscope 40 for observing the shielding positional relationship between the mask 2 and the sample 3 is configured separately from the vacuum chamber 15 and can be arranged at an arbitrary location. The optical microscope 40 includes a known loupe 12 and a loupe fine movement mechanism 13. Further, the optical microscope 40 is provided with a fixed base 42 on the observation table 41 for mounting the sample mask unit fine movement mechanism 4 with the sample mask unit 21 removed from the vacuum chamber 15 as shown in FIG. There Te, the sample mask unit fine movement mechanism 4 established a sample mask unit 21 in the reproducible fixed position by the shaft and the hole for positioning as shown in FIG. 9 is placed on the fixed base 42.

  FIG. 10 shows a state in which the sample mask unit fine movement mechanism 4 on which the sample mask unit 21 is installed is fixed on the fixed base 42.

  FIG. 11 is an explanatory diagram showing a method of aligning a portion of the sample 3 whose cross section is to be polished with the center of the ion beam. A photosensitive paper or the like is attached to the sample holder 23, and the trace formed by irradiating the ion beam, that is, the center of the beam and the center of the loupe are driven by the loupe fine movement mechanism 13 to drive X2 and Y2. The sample mask unit fine movement mechanism 4 on which the sample mask unit main body 21 after the sample 3 is installed in FIG. By adjusting the position of the fixing base 42 in the X3 and Y3 directions to match the center of the loupe, it is possible to match the center of the ion beam and the part to be cross-polished.

  Thus, when adjusting the shielding position relationship between the mask 2 and the sample 3, the sample mask unit fine movement mechanism 4 provided with the sample mask unit 21 is detached from the sample fine movement base 5 and mounted on the fixed base 42 of the optical microscope 40. Then, the mask 2 has its shielding position relative to the sample 3 adjusted by a mask position adjustment unit (mask fine adjustment mechanism).

  FIG. 12 is an explanatory diagram showing a method of mirror polishing the cross section of the sample 3 with an ion beam. When the argon ion beam is irradiated, the sample 3 not covered with the mask 2 can be removed along the mask 2 in the depth direction, and the surface of the cross section of the sample 3 can be mirror-polished.

  In this way, the sample mask unit fine movement mechanism 4 provided with the sample mask unit 21 including the mask 2 in which the shielding positional relationship with respect to the sample is adjusted during ion milling is returned to the sample fine movement base 5 and attached.

  As described above, when adjusting the shielding positional relationship between the mask 2 and the sample 3, the sample mask unit fine movement mechanism 4 on which the sample mask unit 21 is installed is detached from the sample fine movement base 5 and mounted on the fixed base 42 of the optical microscope 40. The sample mask unit fine movement mechanism 4 in which the sample mask unit 21 provided with the mask 2 having the adjusted mask position relative to the sample is adjusted in the vacuum chamber 15 is adjusted during ion milling. An ion milling method is provided that is returned to and mounted on the sample fine movement base 5.

  In recent years, particularly in the semiconductor field, it has become important to observe a cross-section of a composite material with an electron microscope, and the importance of mirror-polishing the cross-section of the composite material has increased. According to the present embodiment, it becomes possible to set the mask accurately and easily at the site where the cross section of the sample is to be observed. In the present embodiment, if a plurality of mask sample units 21 are provided, it is possible to prepare a large number of samples in a state where the mask position is finely adjusted in advance, which is very efficient.

It is a schematic block diagram of the ion milling apparatus by one Example of this invention. It is a schematic block diagram of a sample mask unit. It is a figure which shows the other example of a sample mask unit. It is a block diagram of the sample holder which fixed the sample. It is a block diagram of the conventional sample holder. It is a figure which shows the state which attached the sample holder of a present Example to the SEM sample stand support part. It is explanatory drawing which showed the method of making the cross section of a sample and a mask into parallel. It is a figure which shows the state which pulled out the sample fine movement base and attached / detached the sample mask unit fine movement mechanism which installed the sample mask unit. It is a figure which shows the state which mounts | wears with the sample mask unit fine movement mechanism which installed the sample mask unit in the optical microscope provided separately. It is a figure which shows the state which mounted | wore the optical microscope with the sample mask unit fine movement mechanism which installed the sample mask unit. It is explanatory drawing which showed the method to match | combine the argon ion beam center and the site | part which wants to grind | polish the cross section of a sample. It is explanatory drawing which showed the sample cross-section grinding | polishing method by ion milling.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Ion source, 2 ... Mask, 3 ... Sample, 4 ... Sample mask unit fine movement mechanism, 5 ... Sample fine movement base, 6 ... Vacuum exhaust system, 7 ... Ion source control part, 8 ... Sample fine movement control part, 9 ... Vacuum Exhaust system control unit, 10 ... flange, 11 ... linear guide, 12 ... loupe, 13 ... loupe fine movement mechanism, 15 ... vacuum chamber, 21 ... sample mask unit, 23 ... sample holder, 40 ... optical microscope, 41 ... observation stand, 42 ... A fixed base.

Claims (1)

An ion beam source that is attached to a vacuum chamber and irradiates a sample with an ion beam, a sample holder that fixes a sample, a sample holder fixture that fixes the sample holder, the sample holder, and a sample fixed to the sample holder A mask that partially shields the sample, a sample rotation unit that rotates the sample holder, a sample mask unit that includes a mask position adjustment unit that adjusts a shielding positional relationship between the mask and the sample, and the mask and the sample In an ion milling apparatus equipped with an optical microscope for observing the shielding positional relationship,
The sample holder has a cross-sectional shape with chamfered corners, and can be rotated by the sample rotation mechanism when attached to the sample rotation mechanism.
One surface side of the cross section of the sample holder is a sample fixing surface,
A said surface in contact with the sample fixing surface perpendicular of the sample holder, the rear surface of the polished to a surface to be observed of the sample, because the male screw portion provided in the SEM sample stage support is screw inserted directly Screw holes are provided ,
The female screw hole, the male screw portion by being threaded directly inserted, wherein the sample holder into which a sample was fixed is to be fixed directly to the SEM sample stage without using the SEM sample stage Ion milling equipment.

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